Villoing D, Drozdovitch V, Simon SL, Kitahara CM, Linet MS, Melo DR,

Abstract
Ionizing radiation exposure to the general U.S. population nearly doubled between 1980 and 2006, due almost entirely to the significant increase in the number of radiologic and nuclear medicine procedures performed. Significant changes in the types of procedures and radionuclides used in nuclear medicine, as well as in detection technology, have led to notable changes over time in absorbed doses to specific organs. This study is the first to estimate per-procedure organ doses to nuclear medicine patients and trends in doses over five decades. Weighted average organ doses per examination to 14 organs of interest were calculated for 17 examination types over 10 5-y time periods (1960-2010) as the product of the percentage of use of each radiopharmaceutical in those diagnostic procedures based on comprehensive literature review, the administered activity, and ICRP dose coefficients; doses per radiopharmaceutical were also provided for each organ, procedure, and time period. The weighted doses to adult nuclear medicine patients from cardiac procedures increased to all organs of interest between 1960 and 2010 except for the urinary bladder wall. From high radiation doses for most other procedures in the 1960s, with up to 0.7 Gy in the specific case of radioiodinated thyroid scans, organ-absorbed doses generally decreased from 1960 to 1990. In contrast, during the 1990s and 2000s, the weighted doses were gradually increased for some procedures, such as brain and skeleton scans. The increasing number of nuclear medicine procedures, specifically cardiac scans and changes in weighted doses, underscore the need to monitor exposure levels and radiation-related disease risks in nuclear medicine patients.